Interpretive Summary: The important honey bee queen production industry on the Big Island of Hawaii is threatened by the recent discovery of Varroa destructor on the island. We tested the pre-exposure level of resistance to mites of three sources of commercial Hawaiian bees and feral Hawaiian bees based on their expression of varroa sensitive hygiene (VSH), i.e., the removal of mite infested brood. Experimental colonies were started in Baton Rouge, LA, from local mite infested bees and test queens from Hawaii. We included reference groups of bees with high VSH, and mite susceptible bees. After worker populations represented the test queens, we added a comb of mite infested brood to each colony for one week and measured the subsequent change in infestation resulting from hygiene. Colonies started from commercial and feral Hawaiian queens hygienically removed similar amounts (33-45% on average per source) of mite infested brood in one week. These responses were numerically intermediate between those of the resistant VSH bees (91% removal) and the susceptible bees (9% removal). There was large colony-to-colony variation within each commercial and feral source. We also measured the mite population growth in colonies during nine weeks. Mite population growth did not differ among the sources although it ranged from -51% for VSH bees to -11 to +53% for the other types. The results indicate that existing commercial and feral Hawaiian bees have some resistance to V. destructor based on hygienic response to mite infested brood. This response in commercial stock probably is derived from selection for general hygiene and from importations of germplasm from the U.S. mainland. The variable response of individual colonies suggests that resistance could be improved by testing and selection within the existing Hawaiian bee population.

Technical Abstract:
The important honey bee queen production industry on the Big Island of Hawaii is threatened by the recent discovery of Varroa destructor on the island. We tested the pre-exposure level of resistance to mites of three sources of commercial Hawaiian bees and feral Hawaiian bees based on their expression of varroa sensitive hygiene (VSH), i.e., the removal of mite infested brood. Experimental colonies were started in Baton Rouge, LA, from local mite infested bees and test queens from Hawaii. We included reference groups of bees with high VSH, and mite susceptible bees. After worker populations represented the test queens, we added a comb of mite infested brood to each colony for one week and measured the subsequent change in infestation resulting from hygiene. Colonies started from commercial and feral Hawaiian queens hygienically removed similar amounts (33-45% on average per source) of mite infested brood in one week. These responses were numerically intermediate between those of the resistant VSH bees (91% removal) and the susceptible bees (9% removal). There was large colony-to-colony variation within each commercial and feral source. We also measured the mite population growth in colonies during nine weeks. Mite population growth did not differ among the sources although it ranged from -51% for VSH bees to -11 to +53% for the other types. The results indicate that existing commercial and feral Hawaiian bees have some resistance to V. destructor based on hygienic response to mite infested brood.